Effects of TiN Thin Films Prepared by Ion Beam and Vapor Deposition Method on Fatigue Strength of High Strength Martensitic Stainless Steels

Abstract

Effects of TiN thin films prepared by ion beam and vapor deposition method on fatigue behaviors were investigated on 13Cr martensitic stainless steel with high tensile strength of about 1900 MPa, under plane bending load condition. TiN thin films of 2μm thick were coated on the surface of plate specimen of 1 mm thick with titanium deposition rate of 2∼10 Å/s, nitrogen ion energy level of 10 keV and nitrogen ion current density of 10 mA/cm². Results of fatigue tests revealed that the coat of TiN thin film raised fatigue resistance of the materials by choosing appropriate coating conditions. Characteristics of the TiN thin films were evaluated from XPS (X-ray photoelectron spectroscopy), XRD (X-ray diffraction pattern), hardness and residual stress measurements. The chemical properties of TiN films were those of crystalline Ti, Ti₂N, TiN and amorphous TiN. High hardness and high compressive residual stress were measured at TiN thin films of specimens attained to high fatigue resistance. Some specimens had defects bigger than the size of film thickness distributed on the specimen surfaces. They revealed low fatigue resistance despite they were coated with TiN thin film under a coating condition of high fatigue resistance.